Background: A state of tolerance may be more easily achieved if fully vascularized and functional donor thymus is transferred to the recipient at the time of whole organ transplantation.
Methods: A composite "thymoheart" allograft was created by implanting autologous thymus into a donor heart 60-90 days before organ procurement. Successful intracardiac engraftment of autologous thymus was documented by histology and by flow cytometric analysis.
Results: Histology of the thymic autografts at explantation revealed viable thymus with preservation of normal thymic architecture. Cells retrieved from thymic autografts 60 days after implantation exhibited the same MHC class I and class II staining profiles by flow cytometry as cells taken from the residual native thymus.
Conclusion: We have created a novel composite organ that confers vascularized and functional donor thymus to heart allograft recipients at the time of transplantation without affecting cardiac function.